The present invention relates to sink drains and, in particular, it concerns a sink drain which integrates a gas trap, and optionally also a waste collection volume and a removable lower cover.
Drainage installations for sinks typically include a number of distinct structures performing a number of distinct functions, as illustrated with reference to an under-sink assembly 100 shown in FIG. 12. A sink drain assembly 125 connects to the aperture of a sink (not shown), and typically includes a strainer including a grating or sieve for preventing passage of waste, which may include hair and objects above a given size. Particularly for kitchen sinks, the waste collection volume may be of relatively large diameter and depth, and typically has a removable “basket strainer” 170 in which waste collects until the strainer is intermittently removed and emptied. The sink drain assembly is typically connected to a pipe or “tailpiece” 120 by a connector, such as by a nut 140.
A further requirement of under-sink plumbing installations is a “trap” 130, also referred to as a “gas trap” or “siphon”, which traps a quantity of water by gravity so as to block escape of noxious sewer gases and odors up through the pipes to the sink. Traps can be implemented using S-bend or P-bend curved pipe sections, or as shown in FIG. 12, using a compact “bottle trap” assembly. The trap must be connected to tailpiece 120, such as at seal 150, and provides an outlet which must also be connected to a pipe (not shown) via a connector, such as nut 160, to connect the outlet of the trap to the wastewater drainage system. In many cases, one or more additional branch tube (not shown) is connected between the tailpiece and the trap in order to allow connection of a sink overflow drain and/or an outlet of an appliance, such as a dishwasher. In many cases, the number of components and complexity of the arrangement is much greater than illustrated here.
The above typical arrangement requires assembly of multiple components with a corresponding number of joints, each with potential for developing a leak. Furthermore, the entire assembly occupies a considerable volume, and in particular, dictates a minimum vertical height of the assembly beneath the sink, thereby limiting usage of the under-sink space and rendering installation problematic in various space-limited scenarios.